Plugging-in switch.



w. s. HARLOW.

meme-m SWITCH. APPLICATION FILED DEC. 1, I913.

1,21 1,940. Patented Jan. 9,1917.

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Witnesses. Inventor.

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WILLIAM S. HARLOW, OF SWAMPSCOTT, MASSACHUSETTS.

PLUGGING-IN SWITCH.

Specification of Letters Patent.

Patented Jan. 9, 1917.

Application filed December 1,1913. Serial No. 804,011.

like characters on the drawings representing like parts. v

Plugging-in switches are provided in electric circuits for the purpose of providing convenient means for introducing testing instruments into the line without interfering with the continuity of service, jthe-path of current being changed toinclude the instrument without interruption of the current. These switches as usually constructed comprise line terminals which arenormally in contact, but may be sprung apart to receive a plug-member having a pair "of terminals connected to the instrument. As usually constructed the line terminals consist of flexible elements secured to a support at one end and yieldably engaging each other at the opposite end. The point of engagement is thus at some distance from the point of support so that if the plug member is carelessly inserted or withdrawn one of the terminals may become bent out of shape soproperly return to contact-- that it will not ing position.-

One object of this invention is to provide a new and improved switch of this character in which the line terminals are strong and rigid where the strain is greatest and so constructed and arranged that the contact will be maintained between them even when one or both terminals are bent considerably out of true position by careless handling.

Another object is to provide an improved plug member in which the contact elements will be of a strong and rigid shape while at the same time forming a plug member which will cause only a small springing movement of the line terminals.

Another object is to provide a positive locking device for normally holding the line terminals in contact which can be easily and readily m d. out of the way when it desiredtointroduce an instrument into the circuit.

In accordance with my invention I provide a switch in which the line terminals are U-shaped, one end of each terminal being securedto a support and the otherends engaging each other with a yielding pressure. A locking member is pivoted to one terminal' andmay swing to engage the other holding them firmly together.

My improved plug member comprises a pair of channel-shaped terminals insulated from each other and secured back to back thereby presenting a thin portion. to be inserted between the line terminals.

The novel features of the invention will be fully disclosed in the following specification and accompanying drawings and will be particularly pointed out in the claims.

Referring to the drawings in which I have illustrated a preferred embodiment of my invention, Figure 1 is a View showing an instrument connected in an electric circuit by means of a plugging-in switch constructed in accordance with my invention. Fig. 2 1s a view in elevation SllOWlIlg the 'line terminals with the locking member applied to hold the terminal members to-' gether. Fig. 3 is a sectional elevation taken centrally of the device. Fig. 4 is a plan view showing the line terminals with the locking member in the position shown in Fig. 2. Fig. 5 is a perspective view of the plug member. Fig. 6 is a side view showing the line terminals with the locking device applied thereto, and Fig. 7 is a sectional view taken on the plane indicated by the line 77 Fig. 5.

Referring to the drawings in detail the conductors of an electric circuit are indi cated diagrammatically at 1. Terminal members 2 and 3are connected in the circuit and secured to a support 4: of insulating material. In the construction illustrated these line terminals are each constituted of a strip of flexible metal bent'in a general U shape, one end being bent back and extended as indicated at 5 and secured to the support as by a screw 6. Binding screws 7 secure the conductors in contact with these terminal members and also serve to assist in sea curing the terminal members to the support.

elements 12 and 13 secured therein. These terminals are preferably channel shaped and are placed back to back with insulating material 14 between them. The flanges embrace the slotted end of the handle and assist in holding the parts in position. A

screw bolt 15 insulated from both terminals clamps the slotted end of the handle together, thus securely holding the terminals in position. .The plug member is thus strong and rigid while presenting a portion of minimum thickness to be inserted between the line terminals. The conductors 16 and 17 to which an instrument may be attached are led into the handle through a hole 18 in one end and each conductor is led through a lateral opening to a position Where it may be conveniently soldered to the corresponding terminal. In Fig. 5. the end of one conductor is indicated as soldered to the terminal at one flange thereof.

The.,open*space between the ends. of each terminal is preferably made as small as possible consistent with thecmovement neces sary when the plug member 10 is inserted and this space in the construction shown is made less than thethickness of the metal.

Bythis construction the other ends of the terminals cannot be bent so far back that they will not return to contacting position for. the reason that the secured ends act as stops to prevent excessive movement. This shape also allows considerable bending of the terminals due to rough handling before the terminals will cease to contact as the point of contact is only a short" distance a fromthe point at which the terminals are secured to the supportand the shape is such that theends will remain in contact during a considerable bending of the body portion of the terminals... These terminalsare slotted longitudinally at the curve orloop portion as indicated at 19 to reducethe cross sectionalarea therebyincreasing the resilience at this point and providing for the reception of a locking member 22. It will be clear that aside pull upon the plug member when inserting or withdrawing would tend to bend theterminalsv at a point near the support at or near the bend indicated at 21. By thus slotting the terminals they can be made comparatively rigid at and near the support, the resilience of the slotted portion pin. Atits opposite end this locking me1nber is split and the ends 24 and 25 thus formed are oppositely bent to engage and embrace the terminals. This locking member is normally left in looking position as indicated in full lines in .2 holding the terminals securely together and may be easily swung back out of the way when it is desired to insert a plug member as indicated in Fig. 3. This locking member is at all times securely connected to the terminal and therefore cannot be mislaid or lost.

By this construction I provide a device in which the line terminals are strong and durable and of a shape to continue to perform their function even if bent considerably out of true position. I have provided a locking device by which the members may be connected together in a simple and eliicient manner, the locking device being so constructed that it is easily swung aside to permit the inser tion of the plug member. My improved plug member is strong and durable and provides terminal members which are so constructed and arranged that they will force the line terminals a minimum distance apart, thus making it unnecessary to provide for excessive springing of such terminals.

In operation when it is desired to introduce a testing instrument such for example. as an ammeter, a plug member such as illustrated, having its terminals connected to the ammeter, is inserted between the line terminals. As will be clear from an inspection of the drawings the plug terminals will be in contact with the line terminals before the line terminals are separated. There will therefore be no interruption in the current as it shifts from one path to the other.

Having fully described my invention what I claim as new and desire to secure by Letters Patent is 1. In a device of the class described the combination with a support of a pair of U- shaped terminals each secured at one end to said support, the free ends contacting with each other with a yielding pressure and a locking member pivoted to the loop of one each other With a yielding pressure, said U- shaped terminals being slotted at their looped portions, and a locking member pivoted to one of said U-shaped terminals in the slot thereof and arranged to swing into the slot of the other terminal and shaped to engage said terminal to hold the terminals together.

In testimony whereof I have signed my name to this specification in the presence of 10 two subscribing itnesses.

WILLIAM S; HARLOW.

Witnesses:

LOUIS 0. SMITH, THOMAS J. DRUMMOND.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, I). G. 

